Engine starter



y Oct. 14, 1930. R, ABELL 1,778,012

ENGINE S TARTER Filed April 6. 1925 /4 /5 C/zi' 2 26 Polla'lz .zel

2M/@QM Patented Oct. 14, 1930 PATENT OFFICE ROLLIN ABELL, OF MILTON, MASSACHUSETTS ENGINE' STARTER Application led April 6,

This invention relates to starters for internal combustion engines, and especially to the type that comprises an axially movable transmission unit having a starting pinion for engaging and disengaging a gear of the engine.

(.)ne difficulty With commercial enginestarters of this type is that-When the engine backiiresit bends or breaks the starting shaft or some other part of the mechanism, or disl lodges the starting motor from its anchorage.

To avoid the more damaging consequences some starters include a spring to transmit rotation to the starting pinion, but when such ,a spring is subjected to the stress of a backfire it breaks. Thus, While the cost of a new spring is not so serious as the damage that Would otherwise occurLthe inconvenience of losing temporarily7 the use of the starter, and

the labor' cost of installing a new spring make the total consequence of spring breakage a matter of considerable moment.

Therefore, one of the objects of the present invention is to provide an improved enginestarter that will automatically relieve itself from the damaging stresses of a backfire or other overload and still be in condition to operate. A feature by 'which this is obtained consists in a novel form of mechanism for shifting the pinion of the transmission unit 3o into gear and applying the starting torque thereto. Unlike most forms of mechanism for this purpose7 this mechanism is formed to yrun out of its driving connection While the starting pinion remains in gear under conditions of abnormally great torque, as when the Aengine backfires or fails to turn While the starting motor is running. i

To utilize the aforesaid mechanism to effect a start under normal conditions the in- Vent-ion consists further in providing a spring to balance the torque and any load Within a safe limit. Thus, by combining the 'balancing spring With driving mechanism of the running-out type, the invention `eliminates all shocks and impacts With respect to both axial movement and torque, in addition to providing an overrunning driving connectionI between the starting motor and the starting pinion to guard against damage to4 v:in the-starting mechanism. Furthermore, the

1925. Serial No. 20,960.

running-out mechanism is organized torestore itself automatically to operative condition after relieving itself from abnormally great torque.

Other features of the invention are hereinafter described and claimed and are illustrated by the drawings.

Figure 1 is an elevation of a starting mechanism embodying a preferred form of the invention.

Fig. 2 is a longitudinal section thereof showing the parts in their initial or out-ofgear position.

Fig. 3 is a longitudinal section showing the transmission unit in gear andi as having passed beyond its normal operating position, l and the operating mechanism as having run out of its operating connection to relieve an abnormal torque.

Fig. 4 is an elevation of the sleeve that relieves`the starting shaft of lateral stresses.

Fig. 5 is a development, on a smaller scale, of a prefererd type of cam vmember for shifting the starting pinion axially.

The journal portion of an electric motor casing is indicated at 10, and the armature shaft at 1l. An outboard extension 12 of this shaft (hereinafter termed the starting shaft) carries the starting mechanism which is arranged close to a spur gear 13 of the internal combustion engine. The gear 13 is shown as carried by the fly-Wheel of the engine, a portion of which is indicated at 14. A bearing sleeve 15 is slipped on the starting shaft and fits into the journal portion 10 to relieve the outboard extension from lateral stress. An internal shoulder 16 of the sleeve abuts against a shoulder 17 on the shaft to maintain the outboard end of the sleeve at the desired distance from the motor casing.

An axially movable transmission unit is arranged on the shaft extension 12. As shown, this unit comprises a starting pinion 18, a barrel-shaped cam portion 19 andan internal bearing portion 2O formed to bear on the shaft extension. A counterbore 21 contains a. compression spring 22 and the outboard end of the sleeve 15, the transmission unit thus having a direct bearing on the sleeve in addition to its bearing on the shaft l extension. The sleeve preferably extends Vacross the face ofthe gear 13 to afford ample bearing surfaceto the transmission unit and H to sustain the lateral stresses of reaction bestud-portions 25v are inthe slots as shown by Figs. 1 and 2 the operating device is nested in the barrel-shaped portion 19, but

Vthe outboard ends of the slots 26 arel open to (permit the studs to run out in operation er abnormal conditions so that theoperatin unitv may i overrun the transmission unit w ile the pinion 18 is in gear. 4See Fig. 3. `The end 4face 27 of the barrel-shaped part 19 is at right angles to the axis of rotation and is annular, except that it is intersected by the cam slots 26. Thus, the entrance of the studs 25 into the slotsy is limited by circuxnferentialportionsv of the barrel-shapedl part 19 which serve as guards to' maintain the pinion in mesh with the gear 13in case of overload or backfire until both the operating unit and the transmisison unit have come to rest. When the device encounters an overload or a backfire the driving portions of the two :units wedge themselves a art, the studs run out of the slots 26 and run on the end face 27, and the transmission unit is there# after 4maintained by the latter in an axially advanced position untilv the parts come to rest with the studs in the open ends of the cam slots, whereupon the reaction of the spring 22 restores the parts to their initial nested relation shown in Figure 1. The cam slots are preferably curved to have graduated are at the steepness or pitch, and the steepest portions outboard end, that is, at the end to'wardwhich the-stud portions move from their initial positions at the inner ends of .A rapidly` increasing force. The

the slots.

The spring 22 is preferably stiff and shorter than the space' provided for it ini the ounterbore 21, to'permit the pinion to move into gear without opposition and then to re-A slst further axial movement with strong and 2O and is sustained y the sleeve 15` and the starting shaft by reason of the shoulders 16 and 17. This does not produce end-thrust of the shaft because the counteractive pressure in the op Ao site direction is also sustained by the s aftthrough the operating connections. j'

Assuming that the transmission unit is in its initial position, as shown by Fig. 1, the pinion 18 pressure is. applied to the sprin 'by the bearing portion.

eing then out of gear, and that K current isapplied to energize the starting motor, vthe shaft 11 will'rotate in the direction indicated by the arrow on Fig. 2. Before the operating connections can fully overcome the inertia of the transmission unit the studs 25 will move the latter axially to mesh the pinion 18 with the gear 13. This will occur before any compression is developed in the-spring' 22, but when the pinion reaches the normal. operating position indicated by broken lines in Fig. 2`but subject to slight variations according to load conditions the spring will have been compressed enough to develop a starting torque suicient for normal loads. Under these conditions the spring will'balance the operating torque and the load, since the studs will still be in the cam slots but will be acting on the steeper parts thereof, and if the engine responds and operates onv its own power it will turn the pinion faster than the shaft 11 and cause a reaction of the cams and studs to shift the transmission unit to its initial position.

On the other hand,.if the engine does not respond, or if it backfires, the studs and cams will shift the transmission unit farther tdf theleft (see Fig. 3), whereupon the studs will run out of the open ends of the cam slots and run around on 'the outboard end of the cam portion 19 without producing any further axial movement. Thus, the effective connection'ofthe operating members will be automatically ruptured to release the operating unit from the engine without disengaging the pinion 18 from the gear 13.

This abnormalI operation does not fully compressv the spring or cause the transmission'unit to strike any positive abutment, since the construction provides suflicient margins of-clearance to avoid such undesirable results. Thef' studs 25 will click over the open ends of the cams until the starting -shaft stops turning, but will eventuallycome to restl in the slots and thus automatically restore 'the parts to operative relation. It is toV be observed that the transmission -unit vdoes not include any slipping parts, disconnectible clutch or driving spring between the pinion and the operating .element 19, but that the running-out feature of the operating elements affords all that is necessary to relieve the torque under abnormal conditions.

What l claim is: l i 1..An engine-starter comprising a starting shaft; an axially movable transmission fastened to said shaft, said unitand said member having one an open-ended reactive cam slot and the other a lug arranged to form an operating connection to shift said axially in opposite directions, and a spring arranged toact on said unit tol develop the starting 4torque for normal loads, said lug and said member being formed and a l n I :unit provided with a starting pinion `arranged onsaid shaft, an operating member,

shift said pinion axially and drive it rotatively, said means and 'said member having initially connected operating portions including an open-ended cam slot and a lug,

andaspring arranged to oppose such axial shifting and to develop the starting torque for normal loads While said slot and said lug are in driving relation, said operating portions being arranged to run out of their driving relation in case of overload and to maintain the pinion in an axially advanced position until the operating member comes to rest.

3. An engine-starter comprising an ax-v pinion to its operative position, said rotary y means including relatively rotatable members of which one is formed With a cam slot of increasing pitch open at its steeper e'nd and the other of which has a lug initially in said'slot, said members being formed and arranged to force said lug out of said open end of said slot in case of overload and to maintain the pinion axially advanced until relative rotation of said members ceases.

4. An engine-starter comprising an axially movable transmission unit including a startingl pinion, a rotary operating member, said member and said unit having one a cam slot open at one end and the other a. cam-engaging stud arranged to shift Said unit axially and drive it rotatively, a spring arranged tol resist axial movement of said unit to balance the torque and normal loads, the range of axial movement afforded by said spring being greater than that produced by said cam and stud and the latter being formed and arranged to run out of said open end of said cam slot in case of overload, and means arranged to maintain said transmission unit in an axially advanced position after such running out of said stud until said operating member and said transmission unit both come to rest.

, .5. An engine-starter comprising a rotary operating unit, a rotary and axi'ally movable, transmission unit provided with a starting part provided With a cam slot of graduated pitch open at one end and closed at the other end and the other one of said units having a stud arranged to cooperate with said slot to shift and drive said transmission unit, the pitch of said cam slot being relatively steep adjacent to said open end but adapted to cause said stud to run'out and run on one vend of said barrel-shaped part in case of overload, said barrel-shaped part being formed to maintain the transmission unit in an axially advanced position until said operating units comes to rest.

6. An engine-starter comprising a rotary operating unit, a rotary and axially movable transmission unit provided with a starting pinion, and a spring arranged to balance the axial effort of said transmission unit against normal loads, said units having cooperative driving parts normally maintained in nested relation by said spring, one of said parts having a cam slot open at one end and the other one of said parts having a lug initially in said slot but arranged to run out of the open end of said slot in case of overload and to maintain said transmission unit in an axially advanced-position until said operating unit comes to rest.

7. An engine-starter comprising a starting shaft, an operating member fastened thereto, an axially movable transmission unit unit having cooperative portions initially nested one in the other, the outer one of said portions having a cam slot and the inner one having a lug tol cooperate therewith to shift the transmission unit axially and drive it rotatively, and a spring arranged to act on said transmission unit to balance the torque and normal loads, said nested portions being formed to run out of nested relation under abnormal loads and thereby rupture the driving connection to relieve the torque.

8. An engine-starter comprising a rotary operating unit, anvaxially movable transmission unit provided With a starting pinion, a spring arranged to balance the starting torque and normal loads by opposing axial movement of said transmissionunit, said units having initially interengaged driving portions formed to Wedge themselves apart with relative axial movementin case of overload, and means arranged to maintain said transmission unit in 'an axially advanced position so that said operating unit mayoverrun said transmission unit until th loperating unit comes to rest.

9. An'engine-starter comprising a rotary operating unit, a rotary and axially movable transmission unit provided ywith a starting pinion, and a spring arranged to balance-the axial effort of said transmission unit against tially annular end Vface at right angles to the axis of 'rotation and' with cam slots intersecting said end face to receive said studs and to cause them to run out and run on said end face in case'of overload, said end face being formed to; maintain said transmission unit in an axially advanced positionl after such running out untilpsaid operating comes to rest.

10. An engine-starter comprising a rotary a operating unit, a'rotary and axially mov'- able Atransmission unit provided with a starting pinion, one of said units having a barrelsha'ped part formed with "a cam slot' that intersects one len d thereof and provides a guard kto restrict the entrance to said'cam slot, the other one of said units having a stud formed and arranged to cooperate-With said cam slot to shift said transmission unit axially and drive it, anda spring arranged'to act on said transmission unit to balance the starting effort against normal loads, said stud ,being arranged to run out of said slot in case of overload and to run on said end of said barrel-shaped part, and being unit in an axially advanced position until said operating unit comes to rest.

11. A combination comprising an engine gear, a starting pinion movable axially into and out of mesh with said gear, two coaxial and relatively rotatable elements having one a cam surface and the other a lugvformed and arranged to coact one against the other to shift said-pinion axially into gear and drive it, aspring arranged'to balance the torque and normal loads by opposing such shifting of saidpiniom said two elements 'i being formed one to overrun the other when.

an overload omhaekre is encountered, and means arrangedto maintain vsaid pinion thereafter in mesh with said gear until both of said elements come to rest, said means v being intersected by an opening through which the lug may pass to permit said spring to demesh said pinion when -said elements come torest.

` In testimony whereof Irhave signature thisl 26th day of March, 1925.

n ROLLIN ABELL.

said guard formed to mamtain said transmission v 

